Wafer level chip scale packaging (WLCSP) is a packaging technology of molding flip chips at a wafer level without using lead frames. WLCSP forms package structures having thinner body sizes. WLCSP is widely used in semiconductor packaging industry.
During packaging process and subsequent reliability test, cracks are frequently generated between layers of package structures. Minor cracks between a protective tape and a molding compound are often observed. Having the presence of minor cracks, it is more challenging to conduct subsequent backside treatment of semiconductor chips formed on the silicon wafer. Moisture, oxygen and other impurities may come into the package structures through the cracks; may erode components inside the package structures; and may affect the performance of the package structures.